“The risks from air pollution are now far greater than previously thought or understood, particularly for heart disease and strokes,” says Dr Maria Neira, Director of WHO’s Department for Public Health, Environmental and Social Determinants of Health. “Few risks have a greater impact on global health today than air pollution; the evidence signals the need for concerted action to clean up the air we all breathe.”

The WHO found that outdoor air pollution was linked to an estimated 3.7 million deaths in 2012 from urban and rural sources worldwide, and indoor air pollution, mostly caused by cooking (!) on inefficient coal and biomass stoves was linked to 4.3 million deaths in 2012.

Because many people are exposed to both indoor and outdoor air pollution, there is overlap in these two numbers, but the WHO estimates that the total number of victims from air pollution in 2012 was around 7 million, which is tragic since it would take relatively little in many of those cases to save lives.

There are lots of big obvious things we can do, such as replace inefficient and pollution small stoves in poorer countries with better stoves or even better, electric cooking. Many countries, like China, could also do a lot to cut pollution at their coal plants and over time phase out coal (which isn't just a problem for air pollution, but also for water and ground pollution and global warming). There are all these low-hanging fruits that would make a huge difference. To see how dramatic the improvement could be, just look at these photos showing how bad the situation was in the US not so long ago (China is just repeating what has gone on elsewhere...).